| Kin Fai Mak, Kathryn L. McGill, Jiwoong Park, and Paul L. McEuen
The paper reports the first observation of the valley Hall effect (VHE) in monolayer molybdenum disulfide (MoS₂) transistors. The VHE is a phenomenon where the valley degree of freedom of electrons in 2D crystals, in addition to charge and spin, exhibits a Hall effect in the absence of a magnetic field. This effect is controlled by the helicity of circularly polarized light used to excite electrons into specific valleys. The magnitude of the anomalous Hall voltage observed is consistent with theoretical predictions, and no VHE is observed in bilayer devices due to the restoration of crystal inversion symmetry. The study opens up new possibilities for using the valley degree of freedom as an information carrier in next-generation electronics and optoelectronics. The experimental results are supported by theoretical predictions, and the findings highlight the importance of valley-dependent electronics and optoelectronics in modern technology.The paper reports the first observation of the valley Hall effect (VHE) in monolayer molybdenum disulfide (MoS₂) transistors. The VHE is a phenomenon where the valley degree of freedom of electrons in 2D crystals, in addition to charge and spin, exhibits a Hall effect in the absence of a magnetic field. This effect is controlled by the helicity of circularly polarized light used to excite electrons into specific valleys. The magnitude of the anomalous Hall voltage observed is consistent with theoretical predictions, and no VHE is observed in bilayer devices due to the restoration of crystal inversion symmetry. The study opens up new possibilities for using the valley degree of freedom as an information carrier in next-generation electronics and optoelectronics. The experimental results are supported by theoretical predictions, and the findings highlight the importance of valley-dependent electronics and optoelectronics in modern technology.